We’ve been researching various component testers, and BrentBXR tipped us about this high-resolution capacitor meter. It’s accuracy is claimed to be around 0.2%, which is much lower than typical capacitor tolerances.
Internal comparators in a PIC16F628 create an oscillator with the capacitor under test. The oscillator frequency is proportional to the value of the capacitor. An internal timer measures the period of oscillation and calculates the capacitance. Most high-accuracy capacitor meters seem to use this technique, it’s something we’ll look at closely in the coming weeks.
High resolution capacitor meter - [Link]